botindaries of the cone and, as before stated, are ancliored to the frame 11. These flexible restraining members extend substantially radially witb respect to the axis of the cone and are adapted to permit the slight bodily vibration of the cone in the direction of its axis in response to the vibrations imparted to it through the rod or plunger 2, but the inextensible quality of the tension members offers a movable force acting in opposition to 10 the vibration of the boundaries of the cone causod by the vibratory waves radiating from the center of the cone and reflected back from the edges thereof so that the regions of restraint of the boundaries of the cone are in 15 effect substantially rigid relatively to the regionsintermediate of the restrained regions so that by properly spacing the restrained regions of the boundaries the phase shift of the reflected waves returning from 20 the restrained and relatively free re gions of the boundaries will have a nodal point at the apex of the cone, thereby neutralizing the eitect of the characteristic standing waves of the cone upon the mechanism through 25 whicli vibration is imparted to the cone. Fiirthermore, the substantial neutralization of the standing waves permits the vibration of the cone in true consonance with the vibrations iniparted to it through the actuating so rod or plunger 2 and consequently translates such vibrations into sounds whicli are subBEST AVAILABLE COP sotmd. 'Wher,,e; a ilawe,con e, j@s eul@l 9.y,@d ba@y,, t;he -mat& oxLo4ciurt @4 LY ,t(> @be, y iperXe6t,l!@Q:.p.rod :is, trausmittod @,there-bonj,, stantially pure and unaffected by such un- - .:It. wili @beiwderstood.,thatthe mechAD'is-M . illur,,triatqd and i]D@. - ,p@rce, cd. -'-f4)rmalx it @tl@a' .:tr'a @nswittjug, IOO Ad heiew. - dWVrit) ea, i:k o@ 'an, e -.other k.Ves @o& -4 )avatus@., 'iii@ludiag -those - LeretofQre .,mout@W ed i n g y z . 1 e a p - i n 9 4 , t 3 _ @ 6 - - @ @ o i b o d . i i t l @ Z i h e @ 4 0 5 spirit and scope of i@-e f6tl6@ving clairus. r @ d t o . , b e . s e c ' u r - e d g @ s o @ n a , : 4 , y , @ i i o Ato@l .@pqver"lat. .,i@pon a @raf ae,4-xU 'Qtuxeoirela@ i p a - i 6 n a n d . e a u s - -a. of ibke vibr&tor y 0 :he-bounda-ri af - iid @wav.,er,, egeet a ir-om t es s 4e,@iAe.@-effects:ol r@iled.Ua the, @e' io@ to, wVi6h said vibr-a,-Wa",VeFk 114ploa@ .g I ,.tor-y f i t , r a ' a l a i i 4 g . s o u u a ' b y ' @ i m - -pressijag m@avejnen ii on.a. xegion t $tr-uet. at,area, 'ana ca'u@in'g alterna aves restructure to vary -in phase -]ID" S. aubst=- tipgylo.-,iwutralize @-flects:of e reflectea .125 waves upon t e ' h reg 'ion to w'liich said vibratory movement is applied. Wben vi@ratory movement is imparted to 3. The method of translating sound by imthe cone at its apex by the vibratory mecha- pressing vibratory movement upon a region fj5 nism of a radio receiving set, or by o-ther vi- of an elastic structure of relatively great area, '130 desirable vibrations as are inherently pro@uced in vibrating cones, or other structures, 35 in which the edoe is eitber wholly free or wholly restrain@'d or improperly partially restrained. be noted that the elastic inextensIt ma y ible restraining meinbers 12, which are illus40 trated at the upper and lo-wer boundaries of the cone 3 in Fig. 1, appear to extend in ,tn angular direction relatively to the plane of the boundary of the cone. Such illustration, 45 of course, is greatly exaggei-ated and the n-iembers are shown in this position merely to illustrate the suspension of the cone which is mainly suppoi-ted from its top with its center of gravity to the left of the plane of .50 the boundary of the cone -%vhich natura ly 1 causes the lower portion of the cone to swill@ll-, to the right and t-he upper portion to the left. The action, however, of these restrainiiig c,oi-ds upon the boundaries of the cone is sub55 stantially radial of the axis of the cone ,tiid the movement of the boundary of the cone caused by the iinpressed vibratory waves and the reflected waves is resisted by the resultant of the tension imposed upon such restraining 60 member which acts in a direction opposite to the direction of movement imparted to the boiindarv by such waves. bmtozy@ -mtaom @are 4impar.4ed to -the andtbe.,wae ,vibrating.;in-:kQusmtiaoe fiw,:vibratiorL.4ir4w.t@y 4olu= -of i air;-in -frout.-,@f 46e.-coiie, The -vibr&taiT. v4ves @whichradiatefrom the -Apex -region-.of the botindo ,te!i thexeof .*re ;a'oix-of the@rest@-rALWt*trpo@e tiorp4inQd i@,egio, DS of the bounda:ries the "phase shift" of --a--er-, ' , @lt uating:,portjano iqf, 4e @ rgflwked. wavw Proa @rta@W Niat -of thereflKted -wa,-v es @at -the,,aLpexa,-fheiconi2@*nd n@.uti.-a lizes-t-he-effedt .,6.f t;tandiug of -the la-t-er'i@kmem-& of @ihe, sCa-nd'ii4g w,&- ,ves @witb,.,tlie @4qolQ,4. @of tlh!4 wee aaism Vhich, -in@pa.-rts ..v,.Ibr.%tory t t e ;no:v -Vex -re py-aetical,wnstrtio.tion -th4ti@thce ==e Qd -o-f .-trszsja)itti4,,,o@,s6@nd @,t5 vasU , 6fher herein des@@T,,iW y @qpei@or to -i@ng tve$ "VA It a

.4 1:,733,751 @'and restraining the 'vibrition of predeter-mined r6gions of the boundaries of said elastic structure in such manner as to vary the phases of portions of the vibratory waves r@flected -from the restrained regions relatively to the phases of said waves therebetween sufficiently to substantially neutralize the effects of the reflected waves upon the region to which said vibratory movement is lo @ applied. 4. Th@ method of translating sound by impressin@ vibratory movement upon: a region of An e astic vibratile structure of relatively %reater area ihan said relxion and e:ffectively 15 1 training the vibratioi@s of predetermined regio"s of th6 boundaries relatively to those of intermediate regions thereof by movable forces actinl, upon said boundaries in direel acement thereof 20 t ed to said struen Ly sound by ]'-Mpressing vibra convex central re re of 25 s aid region and a re-entrant sound-projecting i ning the -vibration of prede.- t,ermined r ns of said elastic structure in such a manner as to vary the phases of por30 tions,of the vibratory waves reflected from the restrained regions rela;tively to the phase of,the,waves therebetween sufficiently to substantially neutralize the e:ffects of the reflected ' waves upon the central region to 35 which@ the vibratory movement is applied and the@eby eiiable the.elasti6 @tructure to impart vibrations to the partiall@ confined column of air in contact@with.the reentrant face there'o'f una:ffected by .@tanding waves or 40 resonance characteristic of the vibratile strueture 6. A device for translating sound comprising a vibratile conical structure having a diameter approximating onefourth of the 45 len h of the maximum wave to be transgt mitted means for imDartinL, vibratory movement to a relatively small @egion of the apex of said cone, a rigid support for the boundaries of said coiie and means anchoring 50 regions of said boundaries to said support at predetermined intervals io p@ovide relatively free portions of said boundaries therebetween operable to cause a phase shift of portions of the waves reflected from said boundaries of 55 such character. as to cause tb6 system of reflected w@ves to have a nodal point at the apex of @aid cone In,testimony whereof I have signed my 60 n,ame t.o this specification. SAM-UEL J. PLIMPTON. 65 BEST AVAILABLE COP'I

3EST AVAILABLE COP@ Patentei Oct. 29, l@29 11733,75il UNITE,D STATES PATENT@ OPPIC,'E, SAXUEL Z. PLIMYTON" OF WOP.CESTEIR,, MASSACHl[tSE'XTS; ASI@IGkbR OF ONt-'RAT, To ROBERT BR, I XTCE STURRUP, OF WORGESTFUR, MA SACHUSE-TTS, AND ONF-7TA TO F,I)WARD w. HANNA,, O.F @ LEICMTER, MASSACHUSETT9 =T@BC03) ANlb"vAiuTus:pok t A"gLAtikd 96"' ii Application filed. Itovetixb@et 25, ltdl. a This@ invention relates to improvemen,ts in methods and apparatus for translating 40und by impressing vibratory mo-Vement upon a regioli of an elastic vibratile 8tructure having .,5 relat'vely greater area than said region, an(i thei object of tl-ie, invention is toreduce the resonance caused by the characte'ristic fre@ quency of vibratiorl of the elastio, vibratile st,ructure when subjected t4j vibratory movelo iiient, and th(@,reby eliminawidistortion of the souild: transniitted thoreby,. it, is well known that when i vibratory matioii is applied to a region, of an elastic@ vi@bmtoily structure, such. as a disk, cone.,, or 15 panel, the motion, in general. wlll be tt-angM-itted,, to the boundaries &nd there reflected ba@k into the7 region upon whieh @uch, vibr6tions are 'iiipressecl In all@, such cases there exists frequencies of vibratioii such that when @o the iilipi@ess@d vibration conwns one-or'more of thes6; frequencies t-here4 mre waveg returning@ ftom the boundaries whicfh are@ in. step 'th t -,vi .h;ose@.. td-vancing. from. the region@ u.T.),ofi whicli@ the vibrations:arffimpressed in:,;,,u;c@ha 26 w,,iy@ ag.to produce so-callad.. "standiinio, wa:veg" oi"resonance vibratiovs," Auy siieh@ structuri?@. whoti use.,(I., iii@ w sonr@d translating device, suah. asi a. lo: tidi spoaker;, bi@ h,i-,,es: selectiv6lv with reo,.-trd t6 theger char--'- 30 ,teteristic frequ@ncies- witli@ a conse@qixent@ di-s-torti-on of the sound; or; mn8ic wh-ich. is being tra,,nsmitt,ed. When a w.,ive is produced. ,tt the r-6gion to which the vibratory movement ig-- a@ppi'@@ed 'i't 3.5 trivels to- the boiindary of the strttcttii@e,. t@at is to a, region where the: ela@stiic, aonstant of the mediumcha@ngegsomewhatsiiddenily,@ and is there reflected. The reflecte@d wa@ve st,,trts back toward theregion. upon wliicii@ it: i@s im40 I)res.-,ed. in a, ch,@inge of phase which-., dep-@n,d,.s iipon, th6 ehara-eter of the-: boii-nda-r.-v;. If: fhe bou-nd-,iT,y is@ a:bsol'iitely ri-gid, the @h.gnge, of phase wil-I be zero and. the re@ffoctocl wqw, will retur-n. in. pbase with th-c inipressed: wavg. 45 Tf the bounda r-.v- is- perf ectlv, free, tliere@ wil-I be@,,r: reversal or "ph-.ise shift7' of th&.re,,fl@-,cted w,ive relttively to the impressed -vvave. I haf'vle di@covered,,that-th-e@@'phnse,4]iift". of Forfii)ns,of.%the?,vibrat-ory wttv-es'@re ffocti2@d-ftoin 50 thebound-axiestof anlel-asticvibratilesf-rupttiT-e iyd. -itsso.. may be utihzed- fa@ netitralize thg eA4@cts 6f th@-:'refi@@dwa-yes ulion.,:the r6gibn to whlch tiiiiiribritorymbvem(iktis!vipplied that the so regi6n@@-W whiel-@t t-h-o; vibratory E@oTefnent is gpplitd! Will N'-g nodal' #Ointv@ith r@spect to r) r, th4@@ Ireflegt@dwavos': ther@by, substantially th.6i e 6f; gandirig- Wavtg gnd sub4,anti-a-ly- proviiit-in@g., iltig r6getier h,, cff the teft 'fttod. I *XIVW@ updai thd!7 regi4Dii. tts whip-h vi15fit-ory: m6veiiient I-S l@ppliq@d.,.. 1- htlve: dis- 60 6OVert@d. thtit th@ig raotlitd Is- Applitdbli@, to till tlio, --iO w ' -f tllo'- b6UA&r SI' 6t fji4B I@Itid" V'f'b -iti-10, ttfm'ttre@ Wklt. that-. it, th, -any 6104d 'wave 1,011gft- 65 By, teigos vf -'tli@ ot41,@@tit tAitW *@bk'tttil@ !4tftfc -W-fd. 19 t@ffiifflte,46@iafide &ie t-6-4 tho@- fteOM '6f'viljfAti6ii 6f. @uct@t- 8trtictiii-e A-te TO fAittcld,,"by:th@6 it. 'th 6 p ti@ 6titl- -fti,,-@ih 6d!- 6 6 iA- 75 ltdft P'&-t4fftfii!ly prises translating sound by impressing *i@ bmfijty MovemeTit,,t,p6h it teedii' df dif qldstic gift@tliti l twiv thaft il6gii5n Aiid; thii,-Oibrffti.ijri ofi"pt@dct8f'ethA.A' it 6 th@e@ bo-ftyii- 80 eltiet'of AieT-@ iii sveh it@ maii. el p . 0 ii6r; otgt,6 th - -hdi%t -f 6f the vibftf6il. *Afes-r4ectld f irdfi@ the Mgiofii : re]-*ti*df f6, th-ie. phA 6@-- of, the oliv@,s therebetween in such a manner ii! @ 85 e6ttg i@ bl@ d ti4RY th 6f-tt.h6' dfl te W@d.#6s dpft:the ftg-i@dy-I tb the@,vibfgtijfy iffovOtdeAC, iW gppli,6di,'. Dig@abo, - m,4@, twu&ir& lftpb)r@ tlf e@ pv@-,Ao-tetmin64,- iagi6ftsf- 6-f- the bouwa@ri@6s is i iiivposed 90 byr w mo@nb@e, fore@-. or,@ fbt.,ee8, otilig! uvon ftfd@ r*ons of @ th-,6 bomdtnts@, ilp dirertion'S thAr@3of carfsed th-er str@iefiir..e,- by buti it; will al o 95 ptisdd, upoir@,@ -i-d re by@, W gims, immovable force. Thd invqmtiaft, alw, comptiges@ thamdffiod 4,,ttmgiatiug-solttl4b3-ir4rbmingvibrat&Y 100

BEST AVAILABLE COP"F 1,733,751 movement upon the outer taci3 -of the central region of an elasti4@, Vibratile structure of relatively great6t,h'ft@A than said region which trant sound-provibration of pre anner as to vaey of elastic vibratile structure, such as cones, disks, or p@nels. Desirably a vibratile structure in the form of a cone is employed as it can be constructed of material having relasmall mass and greater rigidity than f types o :,61astiiz vibr atile structures. The method herein described will, therefore, the phases of portions of the vibrat6-iy'iii@F6s---Ee-iio-'i6 fully described in its application to refle6t:ed from ther"6striiiied' i@gions rela';-' a cbnical -sound traiislatin(y d6vice such as tively 't6 the phases of '-w'ave's' therebetw'e-"e-n' 'the;6one - type of 'loud speaker employed in iliz'- thi@ -@f- I kadio rec'eiving appblratus. sufficiently to substantially neutr e fects of the reflected waves upon the region An illustrative embodiment of the invei-ito wh ch the vibf@to 'M'bve@ nfo'iif iion is- shown:'in the accompanying drawings, In usual sound translating deyiees, such as in whic ' h'. 15 loud speakere;, the vibi@@i6ns'-'a-r'e"t'r-ans'm'iite'd" 'Fig. 1 iLs a vertical central sectional view from the convex.@surface of acone-or coneavo through a pjreferred type of conical loud .convex disk the boundary of - which is eifher -speaker; free or is restrained:tl@r'oughout. ..I -n either case standing @@ound w.aves @Ar'e developed -20 wliieh interfere,.with ...:the@ proper reprod,uction or: translation': of ..the-.,music ,or,, otb@Br @;ound. By,the'methodembodyingthe,present invention such undesirable;waves,,arO,, avoided and interfereneg@@with the proper, impres@ioia ,,6 of vibrat ' ory mov,ement up6n,,tbe elastiQ,.strji67 tur,e is oliminated.':'Fur-theriAore@., by:'reason of this inveiati'on the ;%4varithges,of @the more -effective transmission of, t4e souiid from'a re-entrant @face ;ire obtained.;as the- eolumn ,30 Of air which lies in'tront'of t@e re-entrant .face, whether of conieal form or of concave -form, is confined to@ a@ kreatfi@ @or,les,s, de-gree -in accordance with the cQnipity@or.. cone Fi-.'2 is a front elevation of the same on a.somewhat reduced.scale. .The appiratus. illustrated comprises a cas- 85 in- .1 -which. may. be. of rectangular or other -form. to enclose@ the usual, electrical mechtnisn-i.,by means of.which a rod or plun,-er 2 is vibrated -,vl-iieh in turn imparts vibration to the -'elastic vibratile structure, such as a go cone 3 , iiiade of sui-table lig . ht material of an elastic, but substan-tially non-resilient ebaracter, stich as blotting -paper or preferably a slieet.prodilet known commercially as "leath@erette".%: The rod or,plungp-i@ 2 desirably is [),5 connec ted to:the ape@ of the cone by relative-ly rigid clarhping members 4 and 5 of -thin Avi@y lioht metal @uch @L@ aluminum. of the surface,@presented.by,.the,.vibratory ;Tlie casing I;may be supportecl in any 3;-, structure and,such partig@l@,..@o@gil@me At of -suitable maniier.,. as for,example by screws loo the column of air inereasesithe.,effectiveness extendin(r. through,tlie back thereof into a of the sound t;@a@Sl@i@sioii, both a@ to stre4gth -wall, i o@i-. suspended by a, cord secured to a and quality, -vei@. gre@tly: relafively- to that suitable e 6 @anchored in the casing, but YPtransmitted from:,the u's@al flat or, co.nvex @preferably.is supported-by an easel construe40 SUr..faces em lo d i louo,. s eakers and -the tion comprising a rear leg 7 and a bracket 8 lo5 p. -y n @p .like. @i,:. Furthermoie, b@. r@ason,,of.tlie presp-nt method,the resonanca of,the elastie,vibratile ui@s@@@ti@liv eliminsted aiid, structure is s it6d @ie, @oi 4,-, tlierefor4@, @the sounds @transmi ub'@@prodi y ..e iced b ''ih .ject to such resonani@e as i usual, horn tybe-6f loudspeakers,in whic.h vl.bration is im@art@d to ihe,col'umn of @ir w @t4in the horn from a relative@y small.vibratilc 50 diaphragm. By proper@ application of restraint to ;pre-determined riagions of the,.boundaries, whieb may be determined by 4@Xperimentation or by .a soinewhat@ complex -mathe - matical -dalculation which n@ed not be,:herein de@crib@d, @the phase@ of :difrerent portions' of't6 reflected waves iiiay-be telatively vdri6d or hiftdd in such a inanner as to produ'c'e a hodal, pbint of .the reflected waves at the region upon which the vibrations@ are -impressed iher6by 'S'Ubstdntially elim7mating the e:ff 'ect of the 'charac'sounding wave's or r'esonance 'of the structure. The m6thod'above de cribed,,may' be'emCZ; ployed to -triinslate oimd from v6,rio'us ty@es havincy legs 9 and'10 to co-operate with the leg .7 @nd which bracket is secured to a rigid frame 11 which surrounds the boundaties of the cone. The f ame illustrated h r erein is of -r6gular polygonal form presenting twelve iio but it will be understood that the numsides, ber of sides of the polygon, or the form of the siipporting frame may be varied as may be reqtiired by the number of points of test raint required, or that the franie may be ii 5 o f circular o@ other form complementary to t he form of the vibratory sound translatinost ructure employed. The particular form of frame is illustrated h erein' as 'indicatiilg a desi@able structure 12 0 whicli will present a maximum ahd uniform st rength ts aiiehorages fol- the restrainino, i hembers 12 which desirably are 6cured at t he junctions of th6 sid6s and extend radially t herefrom to their points of attachment to 1 25 s epa@ated regions of the boundaries of the c one. Th6 restraining'membbrs 12 desirabl@ are i nextensible flexible cords which are suitably secured at' predetermined intervals to the 130